Safety and efficacy of linuron with or without an adjuvant or S-metolachlor for POST control of Palmer amaranth (Amaranthus palmeri) in sweetpotato

Abstract

Field studies were conducted to evaluate linuron for POST control of Palmer amaranth in sweetpotato to minimize reliance on protoporphyrinogen oxidase (PPO)-inhibiting herbicides. Treatments were arranged in a two by four factorial where the first factor consisted of two rates of linuron (420 and 700 g ai ha−1), and the second factor consisted of linuron applied alone or in combinations of linuron plus a nonionic surfactant (NIS) (0.5% v/v), linuron plus S-metolachlor (800 g ai ha−1), or linuron plus NIS plus S-metolachlor. In addition, S-metolachlor alone and nontreated weedy and weed-free checks were included for comparison. Treatments were applied to ‘Covington’ sweetpotato 8 d after transplanting (DAP). S-metolachlor alone provided poor Palmer amaranth control because emergence had occurred at applications. All treatments that included linuron resulted in at least 98 and 91% Palmer amaranth control 1 and 2 wk after treatment (WAT), respectively. Including NIS with linuron did not increase Palmer amaranth control compared to linuron alone, but increased sweetpotato injury and subsequently decreased total sweetpotato yield by 25%. Including S-metolachlor with linuron resulted in the greatest Palmer amaranth control 4 WAT, but increased crop foliar injury to 36% 1 WAT compared to 17% foliar injury from linuron alone. Marketable and total sweetpotato yield was similar between linuron alone and linuron plus S-metolachlor or S-metolachlor plus NIS treatments, though all treatments resulted in at least 39% less total yield than the weed-free check resulting from herbicide injury and/or Palmer amaranth competition. Because of the excellent POST Palmer amaranth control from linuron 1 WAT, a system including linuron applied 7 DAP followed by S-metolachlor applied 14 DAP could help to extend residual Palmer amaranth control further into the critical period of weed control while minimizing sweetpotato injury.

Selectividad de herbicidas en camote (Ipomoea batatas (L.) Lam.) variedad Criollo

“…Los resultados de selectividad observados para los herbicidas clomazone, pendimetalina, metolaclor y linuron aplicados seis días después de la siembra del camote, concuerdan con lo reportado por varios autores, cuando aplicaron estos herbicidas bajo condiciones similares en otras variedades de camote, tal es el caso de clomazone (Aparecido dos Santos et al, 2018;Correia & Carvalho, 2021;Dittmar & Boyd, 2020;Harrison & Jackson, 2011;Lugo-Torres & Díaz, 2007;Porter, 1990;Wadl et al, 2020), pendimetalina (Hormenoo, 2021;Meyers et al, 2020), metolaclor (Dittmar & Boyd, 2020;Glaze & Hall, 1990) y linuron (Aparecido dos Santos et al, 2018;Correia & Carvalho, 2021;Moore et al, 2021).…”

“…El uso de herbicidas en posemergencia sobre el cultivo, está limitado durante los primeros siete días después de la siembra, lo que obliga a los productores a controlar las arvenses en estados más tardíos del cultivo, pero siempre dentro del período crítico de competencia. Los herbicidas linuron y metribuzin también son efectivos para el control de especies dicotiledóneas en posemergencia temprana (Meyers et al, 2013;Meyers et al, 2017;Moore et al, 2021); mientras que el metribuzin, además ha sido efectivo contra Commelina diffusa, especie que se ha incrementado en varios cultivos, incluidas las plantaciones de camote debido a que no es controlada por otros herbicidas preemergentes que se utilizan en este cultivo (Herrera-Murillo & Picado-Arroyo, 2023).…”